Note 9 - Other Income (Expense), Net - Interest and Other Income Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest income	$ 23,363	$ 14,369	$ 11,637
Amortization of discount (premium) on available-for-sale securities, net	5,277	(4,375)	(4,674)
Gain (loss) on deferred compensation plan investments	8,505	(6,600)	4,563
Charitable contributions	(14,850)	(5,900)	(1,500)
Gain on sale of equity investment	1,424	(0)	(0)
Other	386	658	(224)
Total	$ 24,105	$ (1,848)	$ 9,802